The popularity of the M4 and AR-15 rifle platforms is mainly due their highly customizable design, allowing user to construct and accessorize a rifle for specific missions, applications, or based on his or her personal preferences. A large number of manufacturers produce and sell aftermarket internal and external components for M4 and AR-15 rifle platforms, each offering specific features and benefits not seen in the traditional rifle design. This allows many owners to assemble rifles which reflect their personal needs and preferences.
One of the aspects which owners of M4 and AR-15 rifle platforms desire is a smaller and easier to store design. This aspect is sought after by the military, the police, and civilian owners of M4 and AR-15 rifles. The main way this aspect is achieved is through the use of collapsible stocks. Collapsible stocks provide a means for decreasing the overall length of the rifle in order to facilitate transport and storage. For the M4 and AR-15 rifle platforms, collapsible stocks had long been thought to have reached their minimum length. Recently some manufacturers have developed collapsible rifle stocks that are now significantly shorter than previously available. However, these products require the replacement of a component that the owners would prefer not to or cannot replace. This component is the bolt carrier. The bolt carrier is the main part of the bolt carrier group assembly which facilitates the extraction of the fired shell case and the loading of a fresh round into the firing chamber from the magazine. The bolt carrier greatly influences the reliability of the rifle, hence the resistance to changing the bolt carrier for shorter stock designs.
One of the main limiting factors for shortening the rifle stock is the minimum compressed length of a buffer spring. While combustion gases from the firing of the rifle drives the bolt carrier group rearward, the buffer spring becomes compressed behind it inside the buffer tube; the buffer tube is the replaceable, rearmost portion of the bore in which the bolt carrier group reciprocates. The compressed buffer spring then drives the bolt carrier group forward, reloading the chamber in preparation for firing the next round. The distance traveled by the bolt carrier group is actually the limiting factor for shortening the stock of a rifle. This limit is directly reflected in the minimum compressed length of the buffer spring. As mentioned above, one of the main ways that current designs achieve a shorter rifle stock is through the modification of the bolt carrier component. As this necessitates the exchange of the bolt carrier, the rifle owner must make the choice between the shorter stock and the preferred bolt carrier that they had previously purchased.
Additionally, the method of unlocking the mechanism for extending or collapsing these new short stocks has been placed on the fixed portion of the stock, which is a location significantly different from traditional designs, which operators have become accustomed.
The present invention is a collapsible stock which provides a means for selectively shortening the overall length of the rifle easily and efficiently without requiring the user to switch bolt carriers. Additionally, the present invention utilizes a release mechanism positioned on the butt pad portion of the stock.